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                [Usaco2006 Jan] The Grove 树木                </h1>
                <p>时间限制：5s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：64MB</p>			</div>
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                                <h3>题目描述</h3><p><p><span style="font-size: medium">The pasture contains a small, contiguous grove of trees that has no 'holes' in the middle of the it. Bessie wonders: how far is it to walk around that grove and get back to my starting position? She's just sure there is a way to do it by going from her start location to successive locations by walking horizontally, vertically, or diagonally and counting each move as a single step. Just looking at it, she doesn't think you could pass 'through' the grove on a tricky diagonal. Your job is to calculate the minimum number of steps she must take. Happily, Bessie lives on a simple world where the pasture is represented by a grid with R rows and C columns (1 &lt;= R &lt;= 50, 1 &lt;= C &lt;= 50). Here's a typical example where '.' is pasture (which Bessie may traverse), 'X' is the grove of trees, '*' represents Bessie's start and end position, and '+' marks one shortest path she can walk to circumnavigate the grove (i.e., the answer): ...+... ..+X+.. .+XXX+. ..+XXX+ ..+X..+ ...+++* The path shown is not the only possible shortest path; Bessie might have taken a diagonal step from her start position and achieved a similar length solution. Bessie is happy that she's starting 'outside' the grove instead of in a sort of 'harbor' that could complicate finding the best path. </span></p>
<div><span style="font-size: medium">牧场里有一片树林，林子里没有坑．</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;贝茜很想知道，最少需要多少步能围绕树林走一圈，最后回到起点．她能上下左右走，也能走对角线格子．牧场被分成R行C列(1&le;R&le;50，1&le;C&le;50)．下面是一张样例的地图，其中&ldquo;．&rdquo;表示贝茜可以走的空地，&nbsp;&nbsp;&ldquo;X&rdquo;表示树林，&nbsp;&nbsp;&ldquo;*&rdquo;表示起点．而贝茜走的最近的路已经特别地用&ldquo;+&rdquo;表示出来．</span></div>
<div><span style="font-size: medium">&nbsp;</span></div>
<div><span style="font-size: medium">&nbsp;<img height="209" width="252" alt="" src="../file/1656_0.jpg" /></span></div>
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<div><span style="font-size: medium">题目保证，最短的路径一定可以找到．</span></div></p><hr/><h3>输入格式</h3><p><p><span style="font-size: medium">* Line 1: Two space-separated integers: R and C </span></p>
<p><span style="font-size: medium">* Lines 2..R+1: Line i+1 describes row i with C characters (with no spaces between them). </span></p>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;第1行输入R和C，接下来R行C列表示一张地图．地图中的符号如题干所述．</span></div></p><hr/><h3>输出格式</h3><p><p>* Line 1: The single line contains a single integer which is the smallest number of steps required to circumnavigate the grove.</p>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;输出最少的步数．</span></div>
<p></p></p><hr/><h3>样例输入</h3><pre>6 7
.......
...X...
..XXX..
...XXX.
...X...
......*
</pre><hr/><h3>样例输出</h3><pre>13</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>Silver</p>
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